Marshalling issue

[srinirocks]

The following is my data structure in unmanaged code...

typedef struct {
        USHORT   flash_char;            /* flash char (default &)         */
        USHORT   flash_time;            /* flash time (ms)                */
 
        USHORT   reserved[3];
} MT_PSTN, *PMT_PSTN;
 

(this is function in unmanaged code that i have to call..)

_DLLIMPEXPORT MT_RESULT CALLING_CONVENTION
MTGetPSTNParams(
    const CHANNEL       nChannel,
    PMT_PSTN const      pRegs,
    PULONG const        pLength
    );
 

Can anybody tell me the corresponing stucture i could use in my managed c# code.. im currently using the following structure.. im going wrong somewhere..

[StructLayout(LayoutKind.Sequential)]
        public struct PMT_PSTN
        {
            public ushort flash_char;            /* flash char (default &)         */
            public ushort flash_time;            /* flash time (ms)                */
 
            [MarshalAs(UnmanagedType.ByValArray, SizeConst=3)]
            public ushort[] reserved;
        } 
 

(corresponding function declaration..)

[DllImport("ntidrv.dll", CallingConvention = CallingConvention.StdCall)]
        private static extern ReturnCodes MTGetPSTNParams(short nChannel, [Out, MarshalAs(UnmanagedType.LPStruct)]PMT_PSTN pRegs, uint pLength);